Process for melt spinning polyoxymethylene filaments having elastic recovery

ABSTRACT

A process for producing filamentary material of an oxymethylene polymer having an elastic recovery at 70* F. of at least about 70 percent when subjected to a strain of up to 50 percent.

United States Patent 11113, 03,044

[72] Inventors MyronJ.Coplan [50] FieldolSearch 264/l76,

Dedham; 210, I68, 231,235, 290, 346 I Howard 1. Freeman, Sharon; JosephS.

Panto, Dedham, all of Mass. References Ciled 211 A lap. NO. 31164 2619UNITED STATES PATENTS I221 Fi c 1 3,048,467 8/1962 Roberts et a1 264 210F [451 m 3,323,190 6/1967 Bolfniew 264/176 F ux [73] Assrgnee CelaneseCorporatlon 3,330,897 7/1967 Tessier 264/176 F New -Y- 3,347,969 10/1967Moelter 264/210 F 3,361,859 1/1968 Cenzato 264/210 F x 341,725 Jam 19641abandmed- 3,432,590 3/1969 Papps 264 210 F x FOREIGN PATENTS 37-12,719 91962 Japan 264/176 F 38-2,02l 3 1963 Ja an 264 176 F Pr" ar E am' erliusFrome 541 PROCESS FOR MELT SPINNING 'g z if H woo POLYAXYMETIIYLENEFILAMENTs HAVING Ammey L Horn ELASTIC RECOVERY 4 Claims, 3 Drawing Figs.

52 us. CI 264/210, ABSTRACT= A Process for producing filamentarymaterial of 264/176, 264/231, 264/235, 264/290, 264/346 an oxymethylenepolymer having an elastic recovery at 70 F. [5 I lm. Cl D0ld 5/12, of atleast about 70 p r ent when subjected to a strain of up to Dolf 3/10 50percent.

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PROCESS FOR MELT SPINNING POLYAXYMETHYLENE FILAMENTS HAVING ELASTICRECOVERY This is a continuation-in-part of Ser. No. 341,725, filed Jan.31, 1964, and now abandoned.

This invention relates to the preparation of relatively elasticfilaments of an oxymethylene polymer.

lt has been proposed to prepare filaments from oxymethylene polymers,e.g., by melt spinning. Such filaments, especially those prepared fromoxymethylene copolymers such as the copolymers described in US. Pat. No.3,027,352 issued to Walling et al., have many outstanding propertiessuch as high strength, stiffness and stability. We have now discoveredan entirely new type of oxymethylene polymer filamentary material which,unlike the filaments of the prior art, possess a high degree ofelasticity after being subjected to a relatively large amount ofstretch, e.g., 50 percent or more at 70 F. These new filaments areparticularly useful in the preparation of elastic yarns for stretchgarments, either alone or in a blend with a nonelastic material. The newfilamentary materials have been found to be superior to known elasticfibers, such as spandex fibers, in such properties as breaking tenacityand stiffness as indicated, for example, by initial modulus.

In the past, of all high polymer solids, only elastomers have beenestablished as a class of the materials that exhibits high elasticity"(i.e., the ability to retract rapidly from a large extension). On themolecular scale, the deformation of elastomers is controlled by anetwork of cross-linked flexible polymer chains, where the cross-linkingresults from either primary chemical bonds or secondary bonding betweenthe chains. Thermodynamically, the deformation has its basis in anentropy effect involving the distortion of polymer chains from theirmost probable configurations in the unstretched state.

Within the class of crystalline or semicrystalline polymers, some with alow degree of crystallinity (e.g., less than perhaps percent) canmanifest rubberlike elasticity, where the crystallites act as thecross-links. However, polymers with an intermediate or high degree ofcrystallinity usually undergo yielding and necking" at large extensions,and this tendency is more marked in unoriented specimens. Somerearrangements of both crystallites and disordered chains as well asdisruption of the crystallites occur at large strains. The resultingmacroscopic deformation of the material is largely irreversible due topermanent changes in the structure on extension.

Elastic hard" (nonelastomeric) polyoxymethylene fibers represent a newclass of elastic polymeric solids of high crystallinity which arecapable of undergoing large elastic deformations due to a specificmorphology present in the material. These materials are prepared in theform of extruded fibers under specific conditions of crystallizationfrom the melt (i.e., crystallization under stress).

The polymers that can be used for formation-of such elastic materialsare oxymethylene polymers, preferably random oxymethylene copolymers ashereinafter defined. After melt spinning, the material is subjected to ahot-wet treatment to improve tenacity and elastic recovery and renderthe material uniformly opaque. The essential morphological feature ofthe hot-wet-treated elastic materials as revealed by X-ray and lightscattering and electron microscopy is the presence of stackedcrystalline lamellae with their normals primarily aligned along thefiber and film extrusion direction. The mechanism of elasticity is basedon a splaying-apart of these lamellae, involving their reversiblebending andv torsional deformation during macroscopic deformation of thematerial. Thus, in contrast to rubber elasticity, where the kineticunits are flexible chain segments, the kinetic units for the elasticityof an elastic hard material are the lamellar crystals. Due to theorientation of the lamellae along the fiber and film extrusiondirection, the elasticity is exhibited almost exclusively in thatdirection.

Although subsequent hot-wet treatment increases the elastic recovery ofelastic materials, the conditions of the initial crystallization processare important with the respect to the route by which a high degree ofelastic recovery is achieved. inappropriate spinning conditions may leadto fibers which exhibit not only a relatively low level of elasticrecovery, but also require comparatively more stringent hotwetconditions to reach a good degree of elastic recovery.

it is accordingly an object of this invention to prepare a new elasticfilamentary material.

It is a further object of this invention to provide an elastic, random,oxymethylene copolymer filamentary material having properties superiorto those of known elastic materials.

it is a still further object to provide a process for the production ofthe above-described elastic filamentary material.

Other objects will be apparent from the following detailed descriptionand claims. 1

H65. 1 to 3 show typical stress-strain curves for filamentary materialsof this invention as more fully described hereinafter at up to 50percent strain (curve A) as compared with the stress-strain curve of oneof the stiffest commercially available spandex yarns (curve B).

In accordance with one aspect of the invention, there is providedfilamentary material of an oxymethylene polymer having an elasticrecovery at zero recovery time (hereinafter defined) at 70 F. of atleast about 70 percent when subjected to a strain, for example, of up to50 percent, and preferably an elastic recovery at zero recovery time ofat least about 75 percent when subjected to a strain of 35 to 50percent. More specifically, the material has at 70 F. an elasticrecovery at zero recovery time of at least about 70 percent, preferablyat least about 75 percent when subjected to a strain (or extension) of50 percent. in particular, filamentary materials having at 70 F. anelastic recovery at zero recovery time of at least about percent or 90percent after being subjected to an extension of 50 percent arecontemplated under the invention.

In general, the elastic recovery after 2 minutes recovery time of theabove-described filamentary material is at least 10 percent greater thanthe values of elastic recovery at zero recovery time. Thus, filamentarymaterials are contemplated under the invention which have an elasticrecovery at 70 F. after 2 minutes recovery time (ashereinafter defined)of at least about 80 percent when subjected to a strain of up to 50percent and preferably an' elastic recovery at 70 F. after 2 minutesrecovery time of at least about percent when subjected to a strain ofabout 35 to 50 percent. More specifically, material is contemplatedwhich has an elastic recovery at 70 F. after 2 minutes recovery time ofat least about 80 or 85 percent, e.g., about 85 to 98 percent, whensubjected to a strain of 50 percent. In particular, filamentary materialhaving at 70 F. an elastic recovery after 2 minutes recovery time ofabout to percent is included within the invention.

The filamentary material of this invention also has comparatively highelastic recoveries when stretched to extensions substantially higherthan- 50 percent. Thus, material is contemplated having at 70 F. anelastic recovery after 2 minutes recovery time of at least about 70percent, e.g., about 72 to 95 percent from a l00 percent strain, and atleast about 60 percent, e.g., about 60 to 85 percent from a percentstrain.

The filamentary material maintains a substantial degree of itselasticity at elevated temperatures. Thus, the filaments may, whensubjected to a strain of 50 percent, have elastic recoveries after 2minutes recovery time of at least about 70 percent, e.g., about 75 to 97percent, at a temperature of 130 F.; at least about 70 percent, e.g.,about 72 to 96 percent at a temperature of F.; and at least about 60percent, e.g.. about 62 to 82 percent at 250 F.

The values for elastic recovery given above are for the first cycle ofstrain and recovery, using the procedure described hereinafter. It hasbeen found in addition that the elastic recovery of the filamentarymaterial between consecutive cycles changes little, after the materialhas been subjected to several cycles of strain and recovery. Thus,material is contemplated which, when subjected to seven cycles of 50percent strain and recovery, has an elastic recovery at 70 F. with zerorecovery time which decreases less than L5, and generally less than 1.0percentage units between the start of the sixth and the start of theseventh cycle.

While various values are given above for elastic recovery after zero and2 minutes recovery time, it should be un' derstood that the material ofthe invention is capable of recovering an additional amount, i.e., mayhave a still higher elastic recovery, when the recovery time issubstantially greater than 2 minutes.

In addition to these elastic properties the filaments generally have,e.g., at 70 F., a breaking tenacity of at least about 1.0, preferably atleast about 1.3, e.g., about 1.3 to 2.5 grams/denier, a breakingelongation of at least about 55 percent, preferably at least about 75percent, e.g., about 75 to 200 percent, and an initial modulus of atleast about 2 grams/denier, preferably about 5 to 30 grams/denier. Thusthe filaments produced under this invention have other good mechanicalproperties as well as elasticity, e.g., stiffness and strength.

The tensile properties of the preferred polyoxymethylene copolymerfibers essentially remain constant on going from room temperature to 190C., including the absence of necking behavior. On the other hand, thecorresponding nonelastic fibers become brittle at the low temperature,reflecting the glassy state of the polymer. The observed superiority ofthe elastic fibers over the spandex fibers at the low temperature isunexpected.

Thus the tensile properties, including elastic recovery, of elastic hardfibers of a polyoxymethylene random copolymer undergo a small changeover the temperature range 1 90 C. to 23 C., compared with nonelasticpolyoxymethylene and spandex fibers. The tensile properties of theelastic hard materials are relatively free from the embrittling effectsof low temperatures, which is commonly observed at temperatures belowthe glass transition of amorphous and semicrystalline polymers. Inparticular, a relatively high value of break elongation of the elasticmaterials at very low temperatures is remarkable. These observationsindicate that tensile deformation of the elastic materials isaccommodated largely by a reversible deformation of lamellar crystals.

In addition to the above mechanical properties, the filamentary materialof the invention generally has a birefringence of at least about 0.03,e.g., from about 0.04 to 0.08, and most often from about 0.05 to 0.07.

A random oxymethylene copolymer, as the term is used above, containsrecurring oxymethylene, i.e., CH O, units interspersed with OR groups inthe main polymer chain where R is a divalent radical containing at leasttwo carbon atoms directly linked to each other and positioned in thechain between the two valences, with very substituents on said R radicalbeing inert, that is, those which do not include interfering functionalgroups and which will not induce undesirable reactions, and wherein amajor amount of the OR units exist as single units attached tooxymethylene groups on each side. A random copolymer may thus bedistinguished over a block copolymer wherein repeating units of eachmonomer make up block segments containing little or no units of anyother monomer. Thus, in block copolymers containing oxymethylene andother units, substantially all of the other units are attached to likeunits rather than oxymethylene units on each side. Particularlypreferred are random copolymers which contain from 60 to 99.6 molpercent of recurring oxymethylene groups. In a preferred embodiment Rmay be, for example, an alkylene or substituted alkylene groupcontaining at least two carbon atoms. Examples of preferred polymersinclude copolymers of trioxane and cyclic ethers containing at least twoadjacent carbon atoms such as the copolymers disclosed in US. Pat. No.3,027,352 of Walling et al.

The preferred random oxymethylene copolymers which are treated inaccordance with this invention are thermoplastic materials having amelting point of at least 150 C. and are normally millable at atemperature of 200 C. They have a number average molecular weight of atleast 10,000. These preferred polymers have a high thermal stability.For example, ifthe stabilized oxymethylene polymer used in a preferredembodiment of this invention is placed in an open vessel in acirculating-air oven at a temperature of 230 C. and its weight loss ismeasured without removal of the sample from the oven, it will have athermal degradation rate of less than 1.0 wt. percent/min. for the first45 minutes and, in preferred instances,

less than 0.1 wt. percent/min. for the same period of time.

The preferred random oxymethylene copolymers which are treated in thisinvention have an inherent viscosity of at least one (measured at 60 C.in a 0.1 weight percent solution in pchlorophenol containing 2 weightpercent of a-pinene). The preferred copolymers of this invention exhibitremarkable alkaline stability. For example, if the preferred copolymersare refluxed at a temperature of about 142-l45 C. in a 50 percentsolution of sodium hydroxide in water for a period of 45 minutes, theweight of the copolymer will 'be reduced by less than 1 percent.

As used in the specification and claims of this application, the termcopolymer" means polymers having two or more types of monomeric units,including terpolymers and higher polymers. Suitable oxymethyleneterpolymers are those having more than two different kinds of monomericunits such as those disclosed in US. Pat. application Ser. No. 229,715,filed Oct. 10, 1962 by Walter E. Heinz and Francis B. McAndrew, whichapplication is assigned to the same assignee as the subject application.I

In accordance with another aspect of the invention, the filamentarymaterial of this invention is formed by melt spinning a fiber-formingoxymethylene polymer, i.e., extruding the polymer in the form of a meltthrough the orifices of a spinneret at a shear rate of about 250 to2,500 reciprocal seconds to form filaments which are taken up at adrawndown" or spin draw ratio of at least about 25, e.g., up to about350, preferably about to 235 when the quench temperature is 70 F. Theproduct as spun may have elastic properties as described above, and maybe formed into a yarn package, or may be subjected to further treatmentas described hereinafter before packaging. In any case, the yarn whichis packaged for ultimate use will have the elastic properties describedabove.

The shear rate of extrusion is defined by the expression 4q/1rr", whereq is the volume rate of extrusion of the molten polymer through eachorifice in cc./sec., and r is the radius of the orifice in centimeters.The shear rate is an indication of the shearing force exerted betweenthe molten polymer of the orifice wall as the polymer is being extruded.

The spin draw or drawndown ratio is the ratio of the velocity of initialyarn takeup to the linear velocity of extrusion of the molten polymer.

In one embodiment of this process, the polymer is melt spun by extrusionthrough orifices having a diameter for example in the range of about 5to 25, preferably about 10 to 20 mils, at a linear speed, for example ofup to about 15, preferably about 6 to 12 feet/min. at a shear ratewithin the range set out above, to form filaments which are taken upinitially at a speed, for example, in the range of about to 1,500,preferably about 450 to 1,050 feet per minute, at a drawdown ratiowithin the ranges set out above. The quench temperature, i.e., thetemperature of air or other inert gas such as stream, nitrogen or argon,at the outlet side of the spinneret, is suitably up to about 285 F. Astack or column must be employed downstream of the spinneret if thedesired quench temperature is substantially above or below the ambienttemperature of air, and may also be useful for better control when airat ambient temperature is used as the quench. However, in the lattercase, the polymer may also be extruded directly into air.

In accordance with another aspect of the invention, the asspun filamentsare afterdrawn or stretched at a temperature up to about 250 F., e.g.,50 to 250 F., at a draw ratio within the range of about 1.2 to 2.3,preferably about 1.3 to 1.5. The stretching may be carried out by firsttaking up the yarn on godet rolls from which it is wound on a packageand stretching in a separate operation, or in a combined operation,wherein the yarn is initially taken up by one set of godet rolls fromwhich it travels to a second set of godet rolls traveling at a speedfaster than the first set so that the cold-drawing step is accomplishedbetween the two sets of rolls.

In another embodiment of the process, the freshly spun filaments arepassed around a frictional device in the spinning cabinet, e.g., asnubbing pin or pigtail guide which prevents all the tension exerted onthe filaments downstream of the frictional device from being translatedback to the face of the spinneret, and the filaments downstream of thefrictional device are cold-drawn, e.g., by taking up the filaments ongodet rolls at a speed greater than that at which they pass around thefrictional device. The overall draw ratio between spinneret face andtakeup rolls may be for example within the ranges given for drawdownratio.

While the yarn so produced possesses a considerable degree ofelasticity, it is preferable to subject such yarn to a secondafterdrawing step in amount sufficient to render the fibers uniformlyopaque, e.g., at a draw ratio within the ranges given above for theafterdrawing step. As is the case when no frictional device is used, thesubsequent afterdrawing step may be carried out in a separate operationwherein the yarn from the freshly spun yarn is taken up on godet rollsfrom which it is wound on a package and is subsequently drawn byconventional means, or as part of a combined operation wherein the yarnfrom the first takeup godet rolls travels directly to a second set ofrolls rotating at a speed greater than that of the first set, with theafterdrawing taking place between the rolls.

The initial spinning operation is carried out in a unit which melts thesolid polymer and pumps it at a constant rate and under fairly highpressure through the small holes of a spinneret. it is generallydesirable to melt spin a polymer having incorporated therein one or morethermal stabilizers. Suitable combinations of stabilizers are shown, forexample, in French Pat. No. 1,273,219.

Melt spinning temperatures, i.e., of the molten polymer being extrudedfrom the orifices of a spinneret, may range from about 380 to 420 F. forthe preferred random oxymethylene copolymers.

The polymer is generally melted by subjecting chips of the polymer tothe action of a heated screw extruder. The chips are suitably betweenabout 200 and 2 mesh. The melt is forced through the spinneret orificesby a metering pump. Generally, a filter or sand pack is maintainedupstream of the orifices to remove particles or gels which might blockthem. Preferably, the polymer is maintained as a melt for not more than20 minutes.

The spinneret may contain, for example, from one to about 500 orifices.Elastic monofilaments, for special uses such as tow rope, may beextruded through orifices up to 100 mils in diameter. The liquid streamsemerge from the orifices, generally downwardly, into a gaseous medium,which may be air or an inert gas and solidify.

Filamentary material having the indicated physical properties and also adenier/filament of up to about 20 and even as low as about 1 iscontemplated within the invention.

The following examples further illustrate the invention. All propertieswere measured at 70 F. unless otherwise stated.

EXAMPLE 1 A copolymer of trioxane and 2 weight percent based on thepolymerizable mixture of ethylene oxide was prepared as described in US.Pat. No. 3,027,352 and aftertreated to remove unstable groups asdescribed in application Ser. No. 102,096, filed Apr. 11, 1961. Thecopolymer was then further stabilized by blending with 0.5 weightpercent of 2,2- methylene bis (4-methyl 6-tertiary butyl phenol) and 0.1weight percent of cyanoguanidine based on the weight of the polymer.

The above-described polymeric composition was melt spun at 400 F. bymeans of a gear pump, downward through a 22- hole spinneret having holediameters of mils and 15 mils in length at a shear rate of about 1,140reciprocal seconds. The resulting 22 filament yam was taken up by godetrolls at a speed of 1,000 feet per minute after passing directly througha pigtail guide located in a column 10 feet long containing air at about8090 F. A total of 8. 17 cc./minute of polymer was extruded through thespinneret, corresponding to a linear speed of 10.68 feet per minute. Thedrawdown ratio was thus 1,000 divided by 10.68 or 93.6.

The yarn obtained by this process was uniformly lustrous but turnedopaque on stretching to yield.

The as-spun yarn was lubricated with 50 percent aqueous polyalkyleneglycol-based Ucon H-6N textile finish and was afterstretched in air atroom temperature 70 F., using a draw ratio of2.3 to l.

The properties of yarn obtained, as spun and afterstretched at roomtemperature, are shown in table 1.

The procedure of example I was carried out except that the extrusiontemperature was 415 F., the spinneret contained 34 holes each, 12 milsin diameter and 18 mils in length, the gear pump was operated so as toobtain an extrusion rate of 4.90 cc./min. corresponding to a linearextrusion speed of 6.48 feet/min, at a shear rate of about 860, the yarnpassed over a kiss-roll where it was lubricated with 25 percent aqueousfatty ester-based Nopocostat 2l52-P textile finish, and was then passedthrough a pigtail guide with one wrap taken around the guide stem. Theyarn was then taken up by godet rolls at a speed of 500 feet/min. withan overall drawdown ratio of 77.

The resulting yarn had alternating patches of opaque and lustrous zoneswith the opaque zones exhibiting a relatively high degree of recoverablestretch.

The patchy yarn was drawn at room temperature (70 F.) at a draw ratio of2 to 1. The resulting yarn was completely opaque, had a total denier of250, a breaking tenacity of 1.2 grams/denier, a breaking elongation ofpercent, and an elastic recovery from 50 percent extension at zerorecovery time of about 80 percent.

The elastic properties of the as-spun or after-stretched filamentarymaterial of this invention may be improved by a heat treatment.Preferably the treatment is a hot-wet treatment, e.g., contact with hotwater or wet steam at a temperature of at least F., e.g. up to about 285F. for a period of at least 1 minute.

The following examples illustrate the effect of a hot-wet treatment ofthe product.

EXAMPLE Ill-V1 The procedure of example 11 was carried out except thatno textile finish was applied, the yarn was passed directly through thepigtail guide rather than being wrapped around the guide stem and yarnwas taken up at different speeds, 250, 500, 750 and 1,000 feet/minute(examples 111 to V1 respectively) corresponding to drawdown ratios of38.6, 77.2, 1 15.8 and 154.3 respectively. The yarn was not subsequentlydrawn. Various mechanical properties, other than elastic recovery, ofthree of the yarns obtained, all of which are lustrous, are given intable 2.

Some values of elastic recovery after 2 minutes recovery time of thefour samples of yarn as spun and after a hot-wet treatment or boiloffi.e., immersion in water under about p.s.i.g. pressure at a temperatureof about 250 F. for

FIGS. 1, 2 and 3 show stress-strain curves (curve A) obtained up to 50percent extension, for the yarns of this example as spun (FIG. 1),afterstretched at 70 F. using a draw ratio of 1.5 (FIG. 2), andafterstretched wet at 170 F. using a draw minutes, were determined afterextensions of 50 percent, 100 5 ratio of 1.4 (FIG. 3). In each case,curve B represents a similar percent, 150 percent, 200 percent and 250percent at temstress-strain curve obtained for the stiffest commercialspanperatures of 70 F., 130 F., 190 F. and 250 F. The results are dex.It can be seen that the yarn included within the invention given intable 3. is in each case considerably stiffer than the spandex, re

TABLE 3.-ELASTIC RECOVERY Temperature of yarn, at

70 F. 130 F. 100 F. 250 F.

Yarn and As Boiled As Boiled As Boiled A8 Boiled extension spun off spunoff spun off spun 011' Ex. 111 (250 tt./

min.) pvrcvnl:

50 8.5, h 07, :1 71M) 110,0 7:1. 0 86.0 44,4 62,6 100 7:1,: 02. 5 (10,587.8 :M, 1 110.1 :14. 5 41.5 mi

Ex. IV (500 1t./

min.) percent:

50 00.8 07,6 80. 2 05.6 74.6 05.2 60.4 71.2 71.6 88.5 50.7 80.0 44.754.3 51.7 45.8 67,7 40.3 60.7 35.3 56.1 40.0 20.5 250 30.4 38.5 Ex. V(750 ft./

min.) percent:

Ex. VI (1,0001t./

min.) percent:

- At 185% extension.

3 At 125% extension.

The data in tables 2 and 3 show that filaments may be obgardless of theaftertreatment. However, the aftertreatment, tained in accordance withthis invention which have very e.g., afterstretching whether dry or wetand using any of varidesirable elastic properties, even at elevatedtemperatures ous draw ratios, results in yarns having differentstress-strain while at the same time having adequate mechanicalproperties characteristics which may be utilized in variousapplications. such as breaking tenacity, breaking elongation and initialThus, the slope of the stress-strain curve of the as spun yarn modulus,and that the elastic properties of the yarn as spun, tapers off rathersharply after a certain stress has been applied using a relatively highdrawdown ratio, are significantly im- (see FIG. 1), whereas this effectis considerably modified by a proved by heat treating the yarn, e.g., bycontacting it for a dry after-stretching treatment (see FIG. 2).Moreover, a hotshort period with hot water. wet after-stretchingtreatment results in a considerable change in the shape of thestress-strain curve, which, after this type of treatment has two pointsof inflection (see FIG. 3). EXAMP v1] The heat treatment, e.g., hot wettreatment described above may be used to improve properties such aselastic recovery of dry afterstretched as well as the as spun yarn.Thus, when the The procedure of example I was followed except that theyarn of this example which was dry afterstretched at 70 F. amount ofmolten polymer extruded through the spinneret using a draw ratio of 1.5,was subsequently immersed in hot was 4.73 ec./min. at a shear rate ofabout 660 reciprocal water at 250 F. and 15 p.s.i.g. for a period of 30minutes, it se on n h r ulting yam w taken p a pee f 1.250 had thefollowing properties: denier- 126; initial modulusfeet/min. resulting ina drawdown ratio of 201. Samples of the 29 grams/denier; tenacityl .7grams/denier; breaking elonyarn were afterstretched at F. in air at drawratios of 1.2, gation94 percent; elastic recovery at zero recovery time1.3, 1.4 and 1.5, and at 170 F. while in contact with a waterafter 50percent extension-92 percent. It can be seen therewet cloth covering ahot metal plate, at draw ratios of 1.2 and fore that a hot-wet treatmentof after-stretched yarn resulted 1.4. The physical properties of theyarns obtained are shown in a substantial increase in initial modulusand elastic in table 4. recovery.

TABLE 4 Draw ratio, at

Property spun 1. 2 1. 3 1. 4 1. 5 1. 2 1. 4

Denier 126 125 122 135 128 130 110 Imtial modulus, grams/demon 26. 9 25.6 25. 4 15. 3 12. 5 20 11 Tenac ty, grams/denier. 1, 45 1.35 1. 53 1.45 1. 59 1. 71 1. 98 Breaking elongation, percent 109 104 104 106 01Elastic recovery from 50% extension at zero recovery time, percent..."78 76. 8 76. 0 77. 6 81. G 81. 0 75 Birefringence, A.. 0.0622 0.06600.0617 0.0613 0.0585 0.0569

sion at 70 F., the elastic recovery of the yarn at the end of the sixthcycle was 82 percent.

EXAMPLE VIII The procedure of example 1 was followed except that theamount of polymer extruded was 3.26 cc./min. at a shear rate of about450 reciprocal seconds, the temperature of polymer being extruded was405 F. and the yarn was taken up at a speed of 1,000 meters/min. and adrawdown ratio of 234. Samples of the yarn were afterstretched in air at70 F. using various draw ratios. Properties of the resulting yarnsamples are given in table 5. In determining the elastic recovery of theyarn, each sample was subjected to seven cycles of 50 percent extensionat 70 F. and the elastic recovery at zero recovery time was measured atthe end of the first cycle and the end of the sixth cycle.

TABLE I Draw ratio ltopel'ty spun 1. 2 1. 3 1. 4 1. 5

[)ctticl 114 107 94 93 101 Initial modulus, grams/denier... 24. 5 18. 715. 3 l0. 8 8. El 'li-nar-ity, grams/demon, u 1. 49 1. 47 1.59 1. 72 1.73 I'm. king elongation, percent. 1211 118 .18 811 88 u t'm-nvt-t'y--1st -yulr-,

pt cut 70.4 711.8 78,1 1 81,0 75.2 lllus. 1' recovery tltll t-yi-lv,

Illlt'tltL 04 (17 70 417 (L Birefringence, A,, 0.01150 0. 01173 0.06030.011411 0.0580

The yarn sample of this example which was afterstretched at a draw ratioof 1.5 as described above, was subsequently subjected to a hot-wettreatment by immersing it in water at 250 F. and 15 p.s.i.g. for 30minutes. The resulting yarn had a denier of 96, an initial modulus of 20grams/denier, a tenacity of 1.6 grams/denier, a breaking elongation of53 percent, an elastic recovery after the first cycle as describedabove, of 91 percent and an elastic recovery after the sixth cycle of 50percent extension as described above, of 82 percent.

EXAMPLES IX and X The procedure of example V111 was followed except thatthe spinneret contained 13 holes, each of which was 12 mils in diameterby 18 mils in length resulting in a shear rate of 1,600 reciprocalseconds, and the resulting yarn was taken up at a speed of 1,000feet/minute with a drawdown ratio of about 90 (example 1X) or at a speedof 1,250 feet/min. with a drawdown ratio of 1 10. Properties of theresulting as spun yarns are shown in table 6.

The following examples illustrate the use of quench temperatures, i.e.temperatures of circulating air in the spinning column downstream of thespinneret, of other than room temperature.

EXAMPLES X1 and XII The procedure of example Vlll was followed exceptthat different conditions of quench temperature, takeup speed anddrawdown ratio were used. These variations in the conditions of theprocess as well as the properties of the resulting as spun yarns areshown in table 7.

The data in the above table illustrates that as spun yarn havingrelatively high elastic recovery may be produced using an elevatedquench temperature.

The values of tenacity, breaking elongation, modulus, stress and straingiven above were determined in a conventional manner with the use of anlnstron Tensile Tester operating at a strain rate of 100 percent/minute.The initial" modulus as the term is used above was determined bymeasuring the slope of the stress-strain curve at the point indicated by1 percent strain. 1

The values of elastic recovery given above were also determined with thelnstron at a strain rate of 100 percent/minute.

After the yarn was extended to the desired strain value, the jaws of thelnstron were reversed at the same speed until the distance between themwas the same as at the start of the test, i.e. the original gaugelength. The jaws were again reversed, i.e., immediately for values ofelastic recovery at zero recovery time, or after 2 minutes for valuesobtained at 2 minutes recovery time, and were stopped as soon as thestress began to increase from the zero point. The elastic recovery isthen calculated as follows:

Total length Final distance when extended between jaws Length added whenextended X100 Elastic recovery:

' cordance with procedures well known in the fiber arts. The

value of birefringence is a measure of the degree of molecularanisotropy of the filament which in turn is indicative of the degree ofmolecular orientation produced as a result of spinning and drawingprocedures.

Although the product and process of this invention have their mostdesirable embodiments in conjunction with random oxymethylene copolymersas pointed out above, oxymethylene homopolymers are also contemplated,e.g. as prepared by the polymerization of anhydrous formaldehyde or bythe polymerization oftrioxane which is a cyclic trimer of formaldehyde.High molecular weight oxymcthylcne homopolymers as well as randomcopolymers may he prepared in high yields and at rapid reaction rates bythe use of acidic boron fluoride-catalysts such as boron fluorideitself, and boron fluoride coordinate complexes with organic compounds,as described in U.S. Pats. Nos. 2,989,585; 2,989,506; 2,989,507; and2.989,509 of Hudgin and Berardinelli, 2,989,510 of Bruni; and 2,989,51 1of Schnizer, as well as in the above-cited U.S. Pat. No. 3027,352 ofWalling et al.

ln addition to the methods disclosed in the above-cited patents, othermethods may be used to prepare oxymethylene copolymers and homopolymerscontemplated under this invention, including those taught by Kern et al.in Angewandt Chemie 73 (6), pages 177 to 186 (Mar. 21, 1961), e.g.homopolymers in which the end groups have been reacted with an alkanoicacid such as acetic acid or an ether such as dimethyl ether. Thesereactants cause stable ester or ether end groups, e.g., acetyl ormethoxy groups, to form at the ends of the polymer molecules.

The elastic filamentary materials of this invention are useful in a widevariety of applications. Because of the importance of theseapplications, they will be described in some detail below, underseparate headings.

REPLACEMENT FOR WRAPPED-CORE ELASTIC YARNS In many applications, rubberor so-called spandex fibers are employed as the core in a wrapped-coreyarn construction, the wrapping being comprised generally of staple orfilament yarns made of conventional high modulus low-stretch fibers suchas cotton, rayon, nylon, etc. The process of wrapping is costly andfrequently difficult to control. The properties of the wrapped yarn aresomewhat unpredictable and often represent only a compromise betweenwhat is desired and what can be achieved by the combination of two ormore yarns assembled and held together under radically different levelsof strain.

For example, a typical double-wrapped spandex core, cotton wrapped yarnmay be produced with the core prestretched 300-400 percent when thewrapping is twisted around it. In the at rest state, the core retractsto some strain lower than that at which it was wrapped, thereby causingthe wrapper yarns to be compressed into a jammed helix configuration.

Subsequent stretching of such a yarn, then, represents the combinedeffect of reextending the core from some already partially stretchedstate and the opening of the jammed helix configuration of the wrapper.The stretch modulus of such a complex combination of material propertiesand geometric structure is easily disturbed by a number of transientvariables in original manufacture and subsequent processing as well asduring use of such yarns and fabrics made therefrom. Moreover, theultimate stretch of such yarns cannot be varied independently of thestretch modulus.

The core wrapper structure attempts to combine the virtues of highelastic recovery from high strain of the core with the relative rigidityof the wrapper. The principal object of such a combination is to achieverelatively high power" of recovery from fairly high extensions.

The elastic yarns of this invention are very suitable for thereplacement of such wrapped-core yarns for many applications. With arelatively high modulus obtained with the yarn of this invention, e.g.,in the range of 2-15 grams/den., compared to spandex yarns with amodulus in the order of 0.2-0.5 grams/den, the yarn of the inventionneed not be prestrained and wrapped in order to'exhibit high stretchpower. Used alone (i.e. without'a wrapper) the yarn of'the invention canprovide substantial reduction in weight and bulk at the same level ofstretch power, extensibility, and recovery. Thus, many fabrics'may bemarkedly reduced in weight and bulk, made more sheer, by their use. Onthe other hand, at the same weight'of yarn, density of weave, etc.,fabrics produced from the'yarn of the invention exhibit substantiallymore power than wrapped-core fabrics.

Used as a single-component yarn, therefore, the yarn of this inventionmay be substituted directly for wrapped-core yarns at considerablesaving in cost and improvement in performance. A typical usefulconstruction is a 3-ply yarn having a total denier of 750 comprised offilaments. Each single yarn is twisted up to 15 t.p.i. and the plyconstruction back twisted to yield a balanced yarn. One familiar withthe art will recognize many variations of yarn denier, twist, plyconstruction, and denier per filament suitable for individualapplications.

REPLACEMENT FOR BARE SPANDEX OR FINE- DENlER STRETCH YARNS Fine-deniercontinuous filament yarns (30 up to denier, for example) comprised of athermosettable polymer (especially nylon) have found considerableapplication in lingerie and intimate" garments. While those yarns havecustomarily been knitted (generally tricot) or woven for such fabrics asstandard yarns, increasing interest is displayed in the use of stretchyarns made therefrom.

Stretch yarns of such thermosettable materials are produced by a numberof techniques such as stuffer-box crimping, twist-set-untwist,edge-crimping, etc. The stretch characteristic is imparted by buildinggeometric distortability into the individual filaments of said yarns.

An alternative approach to the use of stretch nylon yarns has beendependent on the application of bare or lightly wrapped spandex yarns.Here the stretch and conformability, of course, depends upon thematerial extensibility of the fiber. Knitted or woven fabrics from suchyarns, however, are generally rather limp and suffer from the relativelylow degree of thermal stability of the typical spandex materials andtheir sensitivity to discoloration and fading in storage and use.

The desirable virtues of either the geometrically stretchy nylon stretchyarns, or the bare or lightly wrapped spandex yarns for lingerie wherestretch and conformability are desired, may be achieved by the use oflight-denier yarns of this invention. A typical application of suchyarns is 70- or IOO-denier stretch tricot fabric for ladies slips.

VARIABLE POROSlTY PARACHUTE CANOPY FABRIC Multifilament yarns of thisinvention which exhibit high elastic recovery from loads approaching 90percent of ultimate rupture are eminently suitable for the fabricationof variable porosity fabrics. A fabric of this type possessingapproximately the following properties may be made from the yarn of thisinvention:

Weight 1-2 ounces per square yard Permeability of 50-90 cubic feet perminute per square foot at 0.5 inches of water pressure differentialUltimate tensile strength of 20 pounds per inch of fabric width in bothwarp and filling directions An exceptionally large permeability at apressure differential that imposes a fabric tensile load of 15 poundsper inch of fabric width.

A typical fabric construction having these properties is as follows:

Fabric Specifications Weight 2 ounces per square yd. Ends per inch Enddenier 60 Picks per inch 130 Pick Denier 60 No. of fils per yarn 21Crimp filling 6 20 lbs/inch of width 20 lbs/inch of width Strip tensilewarp Strip tensile filling Ultimate Elongation Warp Ultimate ElongationFilling Yarn Properties Yarn Denier I30 No. of filaments Zl T.P.l. 0.5Ultimate Stress 1.5-2.0

Ultimate Elongation 75% Stress at 20% 1.0 g.p d Elastic Recovery at 20%Strain 99% Elastic Recovery at 50% Strain 85-90% Fabric PerformancePorosity at low strains: 50-90 cubic feet per minute per square foot at0.5 inches of water pressure differential 1.000 cubic feet per minuteper square foot at 4.0 inches of water Porosity at a stress of poundsper inch of fabric width:

7 WOVEN FOUNDATION GARMENTS, ELASTIC BANDAGES, AND LIKE PRODUCTS FabricWeight 4 ounces per sq. yd, Warp-Acetate I40 denier Ends per inch 65l"illing-yarn of this invention 200 denier Picks per inch 60 Elasticrecovery at 60% strain 95% Stretch level 50% 45 lbs. per inch ofwidth 40lbs. per inch of width Rupture tenacity warp Rupture tenacity fillingModulus in pounds at 40% strain 10 lbs. per inch ofwidth Other stretchfabrics also rely upon the incorporation of bulked/stretch yarns orspandex-type yarns in combination with other less extensible yarns. Theelastically recoverable yarns in some of these fabrics comprises, forexample, from 5 to 65 percent of the fabric which performs elasticallyup to strain levels of 100 percent in the elastic direction.

A typical ski pant fabric utilizing the material of this inventioncontains l50 ends per inch of 70-denier, 2l-filament yarn of thisinvention and 42 picks per inch of 700-denier, 2-fold worsted yarn, andhas a plain weave stretched. This abrupt large change in modulus isoften undesirable, and can be avoided by using the filamentary materialof this invention as the covering yarn. By varying the angle of wrap ofsuch yarn, modulus values, extending over a range of extension ofsignificantly more than 100 percent, can be varied from those typical ofspandex up to those typical of the yarns of this invention and themagnitude of any changes in modulus with extension can be reducedgreatly from those resulting from the use of conventional fibers in thewrapping yarn.

BLENDS WITH OTHER FIBERS Spun stretch yarns composed predominantly ofconventional fibers such as cotton, wool, nylon, polyester, or othercommonly used materials, can be produced; by blending such fibers with 5to 45 percent of staple fiber of this invention. Such blending iscarried out in a card, pill box, pin drafter, Pacific Converter, orother normally used blending procedure prior to spinning the yarn. Therelatively high modulus of the fiber of this invention makes theseblending operations much easier to control than when other elasticfibers having a much lower modulus are used, and drafting and spinningare accom plished with only minor adjustments of normal machinesettings. The final product can be used to produce fabrics having usablestretches in the range of 10 to 30 percent, and the high recoverabilityand high recovery energy provided by the filamentary material of thisinvention ensures excellent elastic characteristics in the stretchfabric, and minimizes or eliminates the problem of pilling encounteredwith low-modulus fibers.

BULK STRETCH YARNS Bulked yarns as presently being produced arecharacterized by being lofty, but not having unusual stretchcharacteristics. Stretch yarns, on the other hand, may be bulky, butthey achieve their stretchiness at the expense of reducing this bulk;that is, by removal of the crimp which causes it. A true bulk stretchyarn would be one in which the bulk is retained when the yarn isstretched. This could be accomplished if the fibers from which the yarnwas made had a low enough modulus to ensure that the yarn could stretchby virtue of the fibers themselves stretching, and not primarily orexclusively by a crimp removal mechanism.

Yarns made from the fibers of this invention can be made bulky bydrawing them under slight tension over a sharp, unheated edge, followedby stretching and relaxing. This causes the filaments to kinkextensively, and results in a very bulky yarn having 50 to percent ofhighly recoverable stretch. Such bulky stretch yarns are useful forproducing light, lofty fabrics, in the range of 3 to 10 ounces persquare yard, having excellent cover and the ability to recover theiroriginal dimensions after being stretched 50 percent or more. Moreover,much of this bulk is retained over wide ranges of stretch, and thus thefabric cover is not seriously reduced by stretching, making it ideal forapplications like bathing suits, formfitting blouses, leotards or otherformfitting garments, etc.

Fabrics for these applications can be made somewhat more open from theyarns of this invention than from other types of stretch yarns, thusproviding the possibility of constructing lighter, more porous and,therefore, more comfortable fabrics.

STRETCH SEWING THREADS One of the current problems in the production ofgarments made from stretch fabrics is to retain that stretch in the seamof these garments. This can easily be accomplished by using a sewingthread which is capable of stretching with the fabric. The sewingthread, on the other hand, must be capable of withstanding the normalstresses imposed by the sewing operation without undue stretch, or seampuckers will result. Sewing threads having the desired characteristic ofgood sewability and capable of providing the stretch needed in the seamsof garments made from stretch fabrics can be made from fiber of thisinvention in a number of ways. One such thread can be produced in normalsewing thread constructions using the filaments of this invention inplace of those made from other fibers. A gradation of stretchability canbe provided by producing yarns from blends of staple fiber made from thefilaments of this invention in varying amounts with cotton, nylon, orother textile fiber, and using such yarns in conventional sewing threadconstructions. Still another suitable yarn for the production ofstretchable sewing threads is one in which normal textile fibers areeither spun or wrapped around a yarn of this invention as core, in anyone ofa number of normal core-yarn-manufacturing techniques.

BULK FILLING MATERIAL fibrous materials, due to poor elastic recoveryfrom bending 6 denier material 3 denier material 50% low modulus 50%medium modulus Staple length 3 inches Crimps per inch offiber lengthSTRETCH NONWOVENS Nonwoven fabrics are relatively stiff materials whichdo not drape or conform to bodily contours as do normally woven fabrics.A method of improving the quality of a nonwoven fabric in terms ofdrapeability and recoverability from imposed strains is to construct thenonwoven in part or entirely from fibers of this invention. The highlyelastic nature of relatively low modulus fibers of this invention in lowdeniers can make them desirable materials for stretch nonwovens.

A typical nonwoven is composed of 1% inch cut staple, low modulus fibersmade from 3-denier filaments of this invention and having a web weightof 2.0 ounces per square yard and a 30 percent by weight low modulushigh-strength adhesive binder.

TUFT ED CARPETS A typical application, taking advantage of the recoveryproperties of the material of this invention is in a rug backing (eitherin total or as a component) for tufted carpets. A tightly woven fabricof suitable construction and weight passes through the tufting machinesunder fillingwise extension and tension (approximately 25 percentextension). The base fabric is tufted in this form after which thefilling tension is allowed to relax. The fabric then contracts, whichcauses the pile to condense producing a heavier and denser pile than cancurrently be obtained by the present rug-backing fabrics (jute, cotton,polypropylene). This procedure produces carpets with a denser pile, andtherefore with a more enhanced and more luxurious-looking pile than cancurrently be produced by prior art methods. Besides the advantage ofappearance, the more compact pile has better resistance to crushing,better abrasion properties, and longer wear, etc.

A typical construction of such a rug-backing fabric is a plain wovenfabric weighing about 9 ounces per square yard constructed from3,100-denier yarns having a yarn count of 12.5 ends per inch of 13 picksper inch. These yarns can be either continuous filament or spun stapleyarns.

WOVEN CARPETS The filamentary material of this invention hasapplications in the woven carpet industry as binding yarns in carpets.The high recovery forces of the yarn and fiber imparts higherandtherefore more desirablebinding forces to the pile than can be obtainedfrom current binding yarns. The higher binding forces also prevent pilepu|lout" and produce a more stable pile and carpet.

The additional ease of extension of the yarn, with high recovery, alsoaids in the formfitting and stability of rugs on stairs, over angles,and around objects. In this application it applies to both the bindingyarns and to the rug pads used underneath rugs.

The fiber is used in both spun staple yarns or continuous filament yarnsin yarn number and construction currently used by the rug industry.

FORM-FIT FABRICS: BEDSl-IEETS, SHIRT COLLARS AND LIKE PRODUCTS A typicalapplication of the filamentary material of this invention which takesadvantage of the high recovery force of the fiber is in the area ofform-fit fabrics such as bedsheets and shirt collars. The advantage ofsuch material in form-fit bedsheets over conventional form-fit sheets isthat the higher retractive forces cause the form-fit sheets to adheremore closely to the mattress producing a neater appearance and a morestable sheet than currently available form-fit sheets.

A typical woven sheeting construction utilizing the material of thisinvention in either continuous filament or staple spun yarns has afabric width of 40 inches, a fabric weight of 4 yards/lb. (3.3 oz./sq.yd.) and a yarn count of 48 warp ends per inch and 48 filling ends perinch.

The same advantages hold true for other form-fit applications such asshirt collars. These applications utilize either woven or nonwovenfabrics containing the material.

GLOVE FABRICS Another typical application for the material of thisinvention, taking advantage of its high recovery and bulking abilityproperties, is in glove wear fabrics including woven, knitted, andnonwoven. The advantages of using such material are better bulkingcharacteristics and better extensibility and recovery performance, andthe resulting fabrics produce better warmth, better comfort, and moreefficient use. The ease of extensibility with high recovery results inmore efficient and comfortable gloves than currently in use.

The material may be used in the production of a wide range of gloveproducts, from work gloves to womens fashion gloves.

UMBRELLA FABRIC A more compact folded umbrella may be made using fabricmade from the yarn of this invention, having the ability to stretch 25percent or more when the umbrella is opened, without serious loss ofcover. This can be accomplished by using a high bulk yarn, so that evenafter the fabric is stretched, the yarn still retains sufficient bulk tofill the fabric interstices and retain the required water repellency.The amount of bulk required varies with the amount of stretch desired,and the construction is adjusted to provide the prime requirement ofhigh cover to provide good water repellency when the umbrella is open(i.e., when the fabric is stretched).

NOVELTY PUCKERED FABRIC The material of this invention is suitable for aseersuckertype fabric in which bands of puckers run lengthwise in thefabric, and are of a size and frequency controlled by the fabricconstruction. These are produced by setting up a warp containingalternating bands of yarns made of any normal textile fiber and of theelastic yarns of the invention.

The latter yarns are wound onto the warp beam under tension sufficientto stretch them 5 or more percent, and this stretch is maintained in theloom by adequate warp tensioning. After weaving, the fabric is permittedto relax, and the high energy of recovery provided by the yarns of theinvention causes the whole fabric to contract, and in turn causes thesurface to pucker in those bands which contain normal warp yarns. Theadvantage of yarns of the invention in such applications results fromits high recovery energy. This permits both very light and very heavyfabrics to be produced more successfully than is possible by currentlyused procedures.

CAMP COT FABRIC The filamentary material of the invention is suitablefor use in camp cot" fabric for both military and civilian applications.The purpose of such material is to provide a small amount of recoverablestretch and thereby provide more comfort in use than is currentlyobtained from present camp cots. The material is suitable for use in allcurrent camp cot fabrics, in plain weave, twills and otherconstructions.

A typical construction for this fabric contains 96 ends per inch by 64picks per inch in a 40-inch width producing a fabric weighing about 2.5yards per pound (5.8 ounces per square yard).

UPI-IOLSTERY FABRICS: OUTDOOR AND INDOOR The filamentary material of theinvention is suitable for use in both outdoor and indoor upholsteryfabrics. Such material imparts better drape, elastic, and formabilityproperties to these fabrics than they currently exhibit. The ease ofextensibility with high recoverability enables easier, more efficientfabrication of the fabric to the furniture as well as producing a neaterappearance after fabrication caused by the high recovery giving a tightor snug fit on the padding and structure of the upholstery.

Current upholstery fabrics come in a wide range of types, weights, andconstruction. The material of the invention may be used, withoutrestrictions, in all types of such fabric either as part of a blend oralone. The material may be in either staple form or in continuousfilament form depending upon the desired end characteristics.

SHOE APPLICATIONS: FABRIC AND LININGS The filamentary material of theinvention finds many applications in the shoe industry in both outershoe and sneaker fabrics as well as inner shoe linings. In use, manyshoe fabrics fail in the area of fabrication to the leather. Because ofthe relative ease of extensibility of the material of the invention,associated with high recoverability, the shoe fabric containing suchmaterial can be fabricated to the shoe with less internal stress. Also,during walking-applicable, to both shoes and sneakers-the fabric extendseasier and recovers more completely thereby producing a more comfortableand longer lasting shoe or sneaker. The lower stresses on the elasticmaterial where the fabric covers the toes results in more comfortableand longer lasting sneakers.

The ease with which fabrics comprising the filamentary material of theinvention-can be formed and coated or impregnated make it very desirablefor shoe linings. Such fabrics adhere to the shape of the shoe easily,without wrinkles, and lend themselves easily to stitching andfabricationof the shoe.

The material isutilized in all presently used shoe fabric and shoelining fabric constructions. It can be'used in the form of spun stapleyarnsor continuousfilament yarns andmay comprise l percent of the fabricor-a component part of the fabric.

COATED FABRICS The material of this invention-is useful in themanufacture of highly elastic coated structures. As is well known tocoaters, soft, drapey, elastic-coated'fabries can be made utilizingcotton knit, goods as contrasted with typical wovencotton sheetings andtwills due to the stretchability of knit fabrics. This stretchability istranslated to the coatedstructure and is useful in forrnable furnitureand automatic upholstery, headliningor for leatherette, as it is known,whichis also used for luggage, etc.

Incoating knittedfabrics with vinyl compositions or other plastic filmsby coatingor lamination, it is generally. noted;that knit fabricsrequire more coating materials to fill the interstices and to obtainlevel, smooth coatings as compared to those same coatings on flat'wovenstructures.

Woven fabrics containing the materiallof the invention exhibit stretchcharacteristics of the knit fabrics whileenjoying the benefits ofcoating virtues of flatwoven-structures. Better overall reinforcementofplastic films also results from compatible characteristics of stretch ofboth the yarn and the plastic film to make better performing products.

Fabricscontaining the elastic material of the invention can beconstructed of either filament or spun yarns as desired and made inroughly comparable weight and strength with typical constructions ofother fibers now used, as for example the woven sheeting of cotton suchas the x80 print cloth of 4 sq. yds. per pound or heavier sheeting ofcoarse yarns as a typical 48x48 construction of 2.6 sq. yds. per pound.Weights and weaves like typical canvas or special weaves as twills anddrills are likewise of use.

To gain extreme extensibility for special uses the material may be knitinto fabrics of structure similar in weight and strength to cotton knitgoods. The stretch of the yarns of the invention added to that alreadyavailable from the knit structure yields coated structures of unusualsoftness, pliability, and elasticity. This enables the coater to producestructures that can be made to conform to odd shapes and around cornerswithout producing unsightly folds or damage to the base fabric.

Coated fabrics using heavy fabrics comprising the elastic material ofthe invention are highly desirable in coated inflatable or air-supportedfabrics. The easy extensibility and high recoverability of this fibermake it easy to fabricate and give a neater appearance at the seamswhile under air pressure. The fabric adjusts itself easier to changes inair pressure under use because of the extensibility and recoveryproperties.

NETS

Nets are extremely open structures formed by knotting together thecomponent yarns at the intersections. They are extremely deformablestructures because of the relative infrequency of the points ofrestriction created by the knots. They have little if any tendency torecover from any deformation. A significant amount of recovery could beprovided by making the nets out of yarns of this invention, which,because of their ability to stretch and high energy of recovery, make itpossible to produce nets with a characteristic not provided by normalnet constructions. Thus, formfitting hairnets, useful over a wide rangeof head sizes, are contemplated from yarns of the invention of denier orless. Expandable containers (e.g. laundry bags) andcarrying bags areeasily produced from heavier yarns, in the range of 100 to 1,000 denieror more. Also, gill nets are contemplated which are designed to catch awider range of fish size than do those made from from conventionalfibers, in which the larger fish are lost because they cannot get theirheads through the mesh. These contain cords or more. than 1,000 denier.

SUPPORT HOSIERY Whereas the majority of support hose utilize relativelycoarse yarn constructions to create the necessary amount of supportstress at a worn strain (anywhere from 0 to 2 pounds per inch of fabricwidth depending upon leg size, position on the leg andamount ofsuppor-trequired) it is possible to utilize yarns of this invention'toproduce, in combination with other materials, a much shearer supporthose.

One technique whereby elastic filaments are utilized is by laying incontinuous filamentelastic yarn within the knit loops of the stocking.Using the filament yarn of the invention, a typical construction for asupport stocking is as follows:

30 denier nylon monofilament with 33 denier filament of the inventionlaid into the knitted mesh Wales er inch Courses per inch Knit structurewith from about 0.5 to 25 mole percent of a cyclic ether having adjacentcarbon atoms at a temperature of from about 380 F. to 420 F. at a sheerrate of from about 250 to 2,500 reciprocal seconds, taking up theresulting filamentary material at a drawdown ratio of from about 25:1 to350:1, subjecting said random oxymethylene polymer filamentary materialto an after-stretching operation at a temperature of from about 50 F. to250 F. and a draw ratio of from about 1.221 to 2.3:1, enhancing theelastic recovery and tenacity and rendering said filamentary materialuniformly opaque by subjecting said filamentary material to a secondafter-stretching operation which comprises contacting said filamentarymaterial with hot H at a temperature of from about 190 F. to 250 F. forat least 1 minute at a draw ratio of from about l.2:l to 2.3:l andforming said filamentary material, which has an elastic recovery at 70F. of at least about 70 percent from an extension up to 50 percent, intoa yarn package.

2. The process of claim 1 comprising subjecting the random oxymethylenecopolymer filamentary material to a quench temperature up to about 285F., a first after-stretching operation at a draw ratio of from about 1.3to 1.5 and a second after-stretching operation at a draw ratio of fromabout 1.3 to 1.5.

3. The process of claim 1 comprising initially taking up the randomoxymethylene copolymer filamentary material at a drawdown ratio of fromabout 25 to 350, continuously advancing said material at a point beyondthe point of initial takeup at a rate greater than that of said takeupsuch that said fully solidified material is drawn at a temperature offrom about 50 F. to 250 F. and a draw ratio of from about 1.2 to 2.3

4. The process of claim 1 comprising taking up the filamentary materialjust subsequent to extrusion at an overall drawdown ratio of from about25 to 350, subjecting said material to frictional contact with a solidsurface at a point intermediate the points of extrusion and takeup suchthat the tension exerted on said material at the takeup point is nottranslated back to the point of extrusion, subjecting said taken-upmaterial to an after-stretching operation at a temperature of from about50 F. to 250 F. and a draw ratio of from about 1.2:1 to 2.3: l,enhancing the elastic recovery and tenacity and rendering saidfilamentary material uniformly opaque by subjecting said filamentarymaterial to a second after-stretching operation which comprisescontacting said filamentary material with hot H 0 at a temperature offrom about F. to 250 F. for at least 1 minute at a draw ratio of fromabout 1.211 to 2.3:] and forming said filamentary material, which has anelastic recovery at 70 F. of at least about 75 percent from an extensionof 50 percent, into a yarn package.

2. The process of claim 1 comprising subjecting the random oxymethylenecopolymer filamentary material to a quench temperature up to about 285*F., a first after-stretching operation at a draw ratio of from about 1.3to 1.5 and a second after-stretching operation at a draw ratio of fromabout 1.3 to 1.5.
 3. The process of claim 1 comprising initially takingup the random oxymethylene copolymer filamentary material at a drawdownratio of from about 25 to 350, continuously advancing said material at apoint beyond the point of initial takeup at a rate greater than that ofsaid takeup such that said fully solidified material is drawn at atemperature of from about 50* F. to 250* F. and a draw ratio of fromabout 1.2 to 2.3
 4. The process of claim 1 comprising taking up thefilamentary material just subsequent to extrusion at an overall drawdownratio of from about 25 to 350, subjecting said material to frictionalcontact with a solid surface at a point intermediate the points ofextrusion and takeup such that the tension exerted on said material atthe takeup point is not translated back to the point of extrusion,subjecting said taken-up material to an after-stretching operation at atemperature of from about 50* F. to 250* F. and a draw ratio of fromabout 1.2:1 to 2.3:1, enhancing the elastic recovery and tenacity andrendering said filamentary material uniformly opaque by subjecting saidfilamentary material to a second after-stretching operation whichcomprises contacting said filamentary material with hot H20 at atemperature of from about 190* F. to 250* F. for at least 1 minUte at adraw ratio of from about 1.2:1 to 2.3:1 and forming said filamentarymaterial, which has an elastic recovery at 70* F. of at least about 75percent from an extension of 50 percent, into a yarn package.